Ships go between the Three Sisters and White Harbor all the time. The Sisters sell crab, fish and goat cheese to White Harbor and in return they sell them wood, wool and hides.[3]Sister's stew is a white seafood stew that is served all over the Three Sisters, in every inn and tavern.[3]

Beacons burn along the shores of the Three Sisters to warn passing ships of danger. The Night Lamp of Sisterton is a prominent beacon operated by House Borrell. Some disreputable Sistermen use false lights to lure ships into wrecks to take their cargo.[3]